To Install & use "regrid" in GrADS

1.  Make a directory "udf" in your grads directory.  "udf" is short
for "user-defined function"

2. Make directory udf/regrid 

3. cd grads/udf/regrid
   ftp to ftp.ncep.noaa.gov (anonymous)
   cd pub/precip/temp/regrid
   prompt
   mget * 
   
4. f77 regrid.f box_ave.f iob.f bssl_interp.f  regrid_util.f indexx.f -o regrid.exe

5. create a file called "udft" in directory grads/udf and place the following lines 
into it:

regrid 1 8 expr value value value value value value value
sequential
full-pathname-to-your-home-directory/grads/udf/regrid/regrid.exe
udf.regrid.gfi
udf.regrid.gfo


6.  In your home directory, add the following line to your ".cshrc" file:

setenv GAUDFT full-pathname-to-your-home-directory/grads/udf/udft

7.  To use "regrid" look at documentation in grads/udf/regrid/regrid.doc

8.  Quick example to use it:

	To interpolate from 144x72 -> 144x73
	
	set gxout fwrite
	set fwrite output_file_name
	set x 1 144
	set y 1 72
	d regrid(cmap,2.5,2.1,1)
	
	
	Regridded CMAP data will be written to file named "output_file_name"
	
	
	You'll need to either log in again  or type source ~/.cshrc to have these
	changes take effect.